Chainsaw Repair

How To Basics - Carb Fixes + Mods - IPL and Service Manuals => How To Basics and Fixes => Topic started by: 1manband on July 25, 2015, 07:07:24 am

Title: things plug
Post by: 1manband on July 25, 2015, 07:07:24 am
cut up a plug,

dodge.  about 20,000 miles on the plug.  computer controlled, fuel injected, etc.

hope it gets clearer as to why, as the thread moves its way along.
Title: Re: things plug
Post by: 1manband on July 25, 2015, 07:35:48 am
at the lower left of this pic, it shows a broken insulator.  this was my first attempt at cutting to find where the ceramic meets the metal.  was a little high, and broke the plug.

this will most likely take a couple of tries to find the correct cut off point.

pencil is pointing to the 'fuel ring'

in each photo, the position of the cut off ground electrode and threaded portion is oriented as if it were attached to the plug.

the bright silvery metallic color below the pencil point, is actually ceramic.  this is very hard material, and will not be cut.  the bright metal was worn and got deposited on the ceramic, came from the HSS cut-off tooling.

Title: Re: things plug
Post by: 1manband on July 25, 2015, 07:38:01 am
some things that can be seen:

-at the ceramic tip, a flow pattern is there.  one of the things that influences where these deposits form is the curved ground electrode.  on the curved side, more deposits.  on the open side, less.

-fuel ring at bottom of plug insulator:  is wider on the ground electrode curved side.  thinner at open side.

some things that i could unfortunately not show clearly in the photos were:

-deposits/color of the top of the metal ring.
-deposits/color on the ground electrode.

there was not an opportunity to show those because the plug was coated with white ash deposits on the exposed metal, this ash is covering what i wanted to show underneath.

-------------------
next hope to compare to 2 stroke plug with some time on it, a few 'plug chop' method plugs in rich, lean and good tune conditions.....etc.

i don't own a electronic controlled carb saw.  if anyone has one, and has access to a lathe or cut-off tool it would be interesting to see your photos.

Title: Re: things plug
Post by: 1manband on July 25, 2015, 09:25:06 am
things fuel ring:

-widest portion of fuel ring = 0.116 inches
-narrowest portion of fuel ring = 0.067 inches

so what to do... with this info.....

need the average.  average = 0.0915 inches.  this is about the width of the ring at the other two sides of the plug on either side of the plug.

going to call this number the 'reference plug'.

assuming that the computer controlled injectors are doing their thing correctly, the factory picked the correct heat range for the spark plug, etc.

going to use this width as a target for the 2 stroke plug.


Title: Re: things plug
Post by: 1manband on July 25, 2015, 12:10:21 pm
up next is a plug from my saw motor.

plug has about 15 tanks through it.

last 2.5 tanks through it:  stumping a 40 inch plus diameter white pine.  air temp high 80's to low 90's.  motor was very hot under heavy load.

fuel ring:

(at least) minimum = 0.095 inch
(at least) maximum = 0.110 inch
approx. 0.1025 inch average

will describe what i see, when time permits.  in short, rich and/or wrong plug heat range for load.

plug and ground orientations shown similarly as in the previous dodge photos.

 
Title: Re: things plug
Post by: 1manband on July 25, 2015, 02:56:52 pm

things are clouded up here, threatening rain....after i woke up from a nap......postponing a brake job.

imo.......

top photo: 
looking at the bottom of the threaded metal portion exposed to combustion.  portion of one side looks clean.  the remainder has black deposits.  shows uneven heat distribution.  if this was wet with fuel after a hot shutdown, rich.  clean area possibly rich washed.  should be colored and color should be uniform around its entirety. 

top photo, 2nd down, 3rd down:
looking at curved ground electrode.  in top photo is is bare of any deposits....getting too hot.  should show deposits about half way on flat section exposed to combustion.  the pencil is pointing to the first signs of deposits on the side of ground.  notice it's down in the curved portion.  electrode is getting too hot in these views as well.

the rest of the photos show a very wide fuel ring.  it will be wider than the dodge plugs.  showed the dodge plug width to establish an example of proper ring and minimum width.

the saw plug was black on on one side of the insulator due in part to ground electrode shrouding coupled with the minuscule distance between the insulator and threaded metal portion of the plug.

the plug in question, is an ngk bpm8y.  going to look for a colder #9 plug replacements and try some different tunings at this point.

don't think the saw will ever see higher loads and heat than it seen in those last 2.5 tanks.  i want to make sure to tune for the most heat soaked and heavy load conditions.

more to come after i get some more plugs.

hope it helps
-joe



Title: Re: things plug
Post by: aclarke on July 25, 2015, 06:16:15 pm
I'll cut a 562 plug now.   Thks for sharing all the pics and info
Title: Re: things plug
Post by: aclarke on July 25, 2015, 06:39:01 pm
Ngk cmr6h.  562xp. Three tanks on plug

[img http://(http://i1184.photobucket.com/albums/z329/Aclarke123/20150725_152919_zpsbfdb13a2.jpg) (http://s1184.photobucket.com/user/Aclarke123/media/20150725_152919_zpsbfdb13a2.jpg.html)/img]
Title: Re: things plug
Post by: aclarke on July 25, 2015, 06:48:16 pm
Ground electrode


[img http://(http://i1184.photobucket.com/albums/z329/Aclarke123/20150725_154426_zps7a0f9d31.jpg) (http://s1184.photobucket.com/user/Aclarke123/media/20150725_154426_zps7a0f9d31.jpg.html)/img]
Title: Re: things plug
Post by: aclarke on July 25, 2015, 06:57:35 pm
Better...

[img http://(http://i1184.photobucket.com/albums/z329/Aclarke123/20150725_155339_zps8017579a.jpg) (http://s1184.photobucket.com/user/Aclarke123/media/20150725_155339_zps8017579a.jpg.html)/img]
Title: Re: things plug
Post by: aclarke on July 25, 2015, 07:06:34 pm
562 was last used to drop a dead Eucalyptus  28" bar  stihl motomix fuel.  About 95f. 
Title: Re: things plug
Post by: 1manband on July 26, 2015, 08:39:32 am
looks like a much better method to cut the plugs!  going to re-cut mine.  thanks for posting.

interesting that the 562 runs a 2 heat ranges hotter plug (#6 heat range) in comparison to the non-strato 590 echo's colder #8 heat range.

if i remember correctly, it is 70C (158F) temperature difference between ranges on NGK plugs.  316F difference in comb chamber temp.

yours still looks cold to me.  stock ignition timing?  maybe a difference in timing is playing between the motors?

jennings says a clean ring tip on the insulator is desirable. another source says the metal center  + electrode should be half clean/half colored.

...fuel ring does seem to fit well with the information in article below......

here's a link to a 45 year old jenning's writing that is one of my references:  http://www.strappe.com/plugs.html

there are some other references to plugs, will post them up, when i find them again.



 
Title: Re: things plug
Post by: 1manband on July 26, 2015, 08:49:51 am
another link, has some alky stuff as well:  http://www.wallaceracing.com/plug-reading-lm.html
Title: Re: things plug
Post by: aclarke on July 26, 2015, 11:50:43 am
The 562 looks like the mix is on the rich side for sure.  This saw has a tab more exhaust and intake timing vs. stock.
By the way the saw runs I'd say it's lean, but the plug seems to tell another story...
Title: Re: things plug
Post by: 1manband on July 26, 2015, 02:52:17 pm
had a plug in a bike that looked very similar to yours.  thought it was the mix. so, fooled and fooled with the carb to correct it.  nope.  then timing.  nope.

turned out to be weak spark.  magnets in the magneto.

don't believe it is your issue, just illustrating how head scratching this stuff can be.

this link shows the effects of timing, a/f ratio, etc. has on required voltage and temperatures in the combustion chamber:  http://www.stealth316.com/2-sparkplugtech.htm

ngk heat range info here:  http://www.ngksparkplugs.com/techinfo/spark_plugs/overviewp2.asp?nav=31000&country=US

your 562 looks like it can feed the fuel.  could it be that the coil is not strong enough to light off the overly rich mix fed in by the port changes?  it looks very cold for a 300F+ hotter heat range plug.

Title: Re: things plug
Post by: aclarke on July 26, 2015, 10:50:35 pm
I'd like to see what a stock 562 with no tweaks looks like...I'll see if I can get a plug from a stock 562
Title: Re: things plug
Post by: 1manband on July 27, 2015, 07:17:17 pm
re-cut the plug.

clearer/easier to measure the fuel ring
 
thinnest = 0.088 inch
widest = 0.140 inch
average = 0.114 inch

there are color differences that my camera cannot pick up.  very bright light is a must.
Title: Re: things plug
Post by: 1manband on July 27, 2015, 07:19:30 pm
I'd like to see what a stock 562 with no tweaks looks like...I'll see if I can get a plug from a stock 562

me too
Title: Re: things plug
Post by: 1manband on August 29, 2015, 07:56:53 am
been busy lately. want to continue along with the science experiment.

can any dealers here get hold of Autolite brand spark plugs?  PM me, have green paper.

the stock plug is an NGK BPM8Y.  seems NGK does not make a colder plug than this.

so am trying to go to a brand that does.

need 3 stock heat range Autolite 2976 or XST2976 (extended tip)

and 3 colder Autolite 2974 or XST2974 (extended tip).

-joe

Title: Re: things plug
Post by: 1manband on September 27, 2015, 06:31:37 am
chevy suburban 5.3 liter v8 fuel injected

average fuel ring width = 0.072"

approximately 20000 miles on this set of plugs.

....notice ash deposits on ground straps.

richest vs. leanest plug.

.....truck thermostat is partially stuck open.  very long warm-up.
Title: Re: things plug
Post by: 1manband on September 27, 2015, 06:38:41 am
lawnmower.

way rich.

fuel ring width = 0.126"

at top..... light color, no carbon
at middle ..... soft sooty fluff
at base.....hard carbon deposit
Title: Re: things plug
Post by: 1manband on September 27, 2015, 06:44:36 am
so far......just accumulating more data.

taking the average of the dodge, echo, chevy, and lawnmower plugs

range:
leanest....0.046"
richest.....0.126"

average of all individual measurements = 0.101" = running target

----------
Title: Re: things plug
Post by: aclarke on September 27, 2015, 10:56:03 am
Cool, takes plug reading to the next level. Very interesting.
Title: Re: things plug
Post by: 1manband on September 27, 2015, 01:07:59 pm
.....maybe?  hahaha.

the one i'm still scratching my head about is the 562 plug of yours.

.....why is that thing is so rich/cold.

could see that it would have a rich idle.  the strato flap is shut, those dang transfers are big enough to drive a truck through.  would need to still be rich at mid throttle, when the flap is just a bit open to accelerate cleanly.  but when the strato flap is opened at high rpm....reason says it would lean out.

only thing i could see happening, is that the strato air plugging pulse first out into the exhaust........is making the fuel charge following super concentrated that is left in the chamber to burn.  too good of trapping efficiency in your ported motor.  donno?
Title: Re: things plug
Post by: aclarke on September 27, 2015, 11:30:06 pm
I monkeyed with the transfer tunnels on that 562. Re-contoured and reduced the area in an attempt to increase the tunnel velocity. Wanted to see how that effected the trans/strato bias. Seemed to work well.  Don't like not being able to easily changed carb settings.

The strato ms201. Is lean of peak as received and makes nice power gains richening them up. Gained rpm going richer.

Title: Re: things plug
Post by: 1manband on September 28, 2015, 05:53:29 am
...those ngk plugs supposedly have a narrow heat range.  maybe they make a #5 plug in that style? ...one range hotter. difficult to see the ring if it's all one color.
the plug you are running looks as if it is not getting up to self cleaning temperature.

different brands may have differences in heat ranges, even if they are the same cross-referenced plug.   10mm or 14mm?

edit: just checked ngk site.  they do make hotter range plugs in that style.

stock: cmr6h
1 range hotter:  cmr5h
2 ranges hotter:  cmr4h

about 100C (200F)difference between each overlapping range. 

Title: Re: things plug
Post by: 1manband on September 28, 2015, 06:23:26 am
ngk heat range and tech guide here:  http://ngksparkplugs.com/tech_support/spark_plugs/p2.asp?mode=nml
Title: Re: things plug
Post by: aclarke on September 28, 2015, 09:23:45 am
Thks for the info. I'll try a hotter plug and see.
Title: Re: things plug
Post by: 1manband on September 28, 2015, 12:06:11 pm
Thks for the info. I'll try a hotter plug and see.

..seems backward not to tune the fuel to the plug.  with the automatic screwdriver carb, not much else you can do.

once you start getting a burn on the ground strap, think you maybe pretty close on heat range.  they say timing, is read on the strap.

...one ignition manufacturer listed their small engine ignitions as putting out a little less than 30 mJ of energy.
compared to a typical MSD ignition for a vehicle runs about 135 mJ.

suspect that this has a lot to do with timing on these small engines.

Title: Re: things plug
Post by: aclarke on September 28, 2015, 12:57:38 pm
I experimented with a total loss electronic ignition on a 372xp race saw to see if it improved the performance with alky and nitro. Had issues with the electronics and never got it running right but I know it would be a huge improvement over stock. I'm gonna revisit this later.
Title: Re: things plug
Post by: 1manband on September 29, 2015, 09:39:56 pm
so far, the car/truck plugs show the leanest and thinnest rings.  water cooled, different animal.  settings for maximum fuel efficiency/lowest emission.

for max power, have to believe the rings would need to be a bit wider, but how much wider?

not enough samples so far to make a determination, imo.  not sure if one will even reveal itself.

need more used plugs to cut up.  chainsaw ones. 

going to give my friend a call who has 3 or 4 crews to see if he could help me out with a pile.  he usually de-carbons and re-rings all the saws during the winter months when work slows.

maybe with 50 or so cut plugs?  cutting only takes a couple minutes per plug.

if anyone would like to contribute some plugs to the effort it would be cool.

thanks
-joe


Title: Re: things plug
Post by: aclarke on September 29, 2015, 09:53:40 pm
I'll yank some out of my work saws and cut em and post pics.
Title: Re: things plug
Post by: 1manband on October 04, 2015, 12:22:25 pm
chart.........so far.

not enough data for the saws yet.

but with 9 sample plugs for the car/truck......the range can be seen.

the "mean line" for each is the average.

will fill in as time goes on.